Method of removing sulphur impurities from petroleum oils



f UNITE-o} STATE Patented Sept. 24,1940 I METHOD OF REMOVING SULPHUR IMPURI- I TIES FROM PETBOLEUMOILS William Alvah Smith, Hamburg, N. Y.

- No Drawing.

Application February 27, 1930, Serial No. 4 1,990

, This invention mates tothe removalof impurities, suchas sulphur, whether in a combined or uncombined condition, from impure hydrocarbon compounds and mixtures thereof. Hereto- 1; fore, it has been common practice to partially remove undesirable impurities, such assulphur compounds, from hydrocarbon compounds and mixtures thereof, some of which maybe unsaturated, by various treating agents, such as the mineral acids, and of which sulphuric acid is the most commonly used or anhydrous metallic halides, such asaluminumchloride, as described in my co-pending patent application Serial No. 393,586, filed September 18, 1929.

In the treatment of certain hydrocarbon mixtures, such, for example, as petroleum compounds and particularly the' distillatesfrom petroleum cracking stills, it has been found that the unsaturated hydrocarbons in those mixtures ordistillates, that is, hydrocarbons containing less than the maximum amount of hydrogen which could be included in the combination, are, to a considerable extent,,polymeriz ed into undesirable or saturated hydrocarbon compounds by the I sulphur. removal agents heretofore employed. Such undesirable or; saturated compounds when burned in an internal combustion engine are more likely to knock or detonate than are the unsaturated compounds before polymerization.

Frequently these polymerized or saturated hydrocarbons have a higher boiling or vaporizing point than is desirable in an internal combustion engine fuel, and therefore are sometimes removed from the desulphurized mixture and discarded, which decreases the yield'of marketable fuel obtained from a given quantity of untreated hydrocarbon compounds. The polymerization of unsaturated compounds into saturated compounds is also frequently undesirable where the compounds are to be used in chemical reactions. For example, the unsaturated compounds are chlorinated more easily than are saturated compounds.

I have discovered that polymerization of the unsaturated compounds into saturated come pounds can be largely prevented or minimized, the sulphur removal action greatly accelerated, and the percentage of impurities removed greatly increased, if the removal action is carried on in the presence of an accelerating or inhibiting agent or substance. By reason'of this, a more desirable product is obtained, and the sulphur removal processes may be performed at temperatures not heretofore feasible or desirable. Various organic compounds have been found suitable as the accelerating or; inhibiting agent, and may be used in the usual methods ,of removing sulphur from hydrocarbon compounds.

The selection of the agent, depends somewhat upon the exact nature of the impurities to be removed, the degrees of, unsaturation'of the hydrocarbon compoundsfrom which theimpurities are to be removed, the amount of impurities to be removed, and the conditions, under which the removal is to be performed. 'In general, I have found that anhydrous treatingagents yield better results-than those in which water dilution ocours, and whensulphuric', acid is used, .I have,

,found that in the presence of an inhibitingagent,

a concentrated sulphuric acid as nearas possible to. a one hundred percent pure acid yields more satisfactory results than does commerciaL-oil .of vitriol acid, which is usually about ninety-five percent strength.; The amount of the inhibiting agent which-it is desirable, to use, while varying somewhat-with the material to be'treated, the impurities, to' beremoved, and thecharacter of, the sulphur removal agent, is in general less than the 'molal quantity of the sulphur removal agent employed.

Among the variousinhibiting agents which may be satisfactorily employed, may be mentioned furfural which is a cyclic aldehyde and nitro-benzene.' The hydrocarbons are treated with the sulphur removal agent, such as sulphuric acid, in the presence of the inhibiting agent, such as furfural or nitro-benzene.-The inhibiting agent may be added to the sulphur removal agent, such as sulphuric acid, before the latter is added to the hydrocarbon mixtures or to the hydrocarbonmixture before the sulphur re-' moval agent is added to the hydrocarbon mix: ture. I prefer to add the inhibiting agent to the hydrocarbon mixture first and then to add the sulphur removal agent to this combined mixture.

After the hydrocarbon compounds or mixtures thereof have been treated with the sulphur removal agent and the'inhibiting agent, the complete mixture may be agitated continuously until the reaction is complete. The reaction I have found is usually completed within about ten minutes when the acid treatment is used for the removal of sulphur. plete, the combined mixture is left quiescent,

whereupon the residue separates out carrying the impurities and the treating agent, which then may be removed in any suitable manner such as by draining off the supernatant liquid, or by treatment with fullers earth or other adsorbent material, or by washing with water. This treated After the reaction is commaterial may then be subjected to any further neutralization or treatment as desired to finish it for the market. The residue may be then disposed of as usual in the industry, or treated for the recovery of any valuable components thereof.

Without the use of the inhibiting agent or material, the acidic sulphur removal treatment often required several hours or days in order to get a whenever the sulphur removal reaction was speeded up by the use of the higher temperatures.

Removal of impurities with such an inhibiting agent may be applied to hydrocarbon mixtures in any stage of refinement or in crude form, and produces a product which I have found will stand exposure to light more satisfactorily than products obtained by similar removal processes Without the use of the inhibitor. The removal of sulphur, when in the presence of the inhibitor, is

, more complete for a given amount of the sulphur removing agent than is possible withoutthe use of an inhibitor, and the inhibitor may be used Without any change in the apparatus used heretofore for sulphur removal.

I claim:

1. The method of removing sulphur impurities from petroleum distillates and oils, which comprises first adding thereto in liquid phase a relatively small quantity of furfuraL-and then treating that mixture with concentrated sulphuric acid in an amount sufficient to remove or render inert the sulphur content of said distillates while inhibiting the polymerization of unsaturated components of said distillates.

2. The method of removing sulphur impurities I have found from petroleum distillates and oils which comprises concomitantly treating said distillates with furfural and with concentrated sulphuric acid in an amount sufficient to remove or render inert the sulphur content of said distillates while inhibitingthe polymerization of unsaturated components of said distillates;

3. The method of removing sulphur impurities from petroleum products, which comprises reacting upon the impurities of such products with furfural and an acidic sulphur removal agent selected from the group consisting of sulphuric acid and aluminum chloride and in quantities sumcient to remove or render inert the sulphur content of said products, while inhibiting the polymerization of unsaturated components of such products.

4. The method of removing sulphur impurities from petroleum products, which comprises reacting upon said products at the same time with furfural and with a concentrated mineral acid, in

amounts sufiicient to remove or render inert the sulphur content of said products while inhibiting,

the polymerization of unsaturated components of said products, the amount of furfural being, in general, less than approximately the molal quantity of the sulphuric acid employed.

5. The method of removing'sulphur impurities from petroleum products, which comprises first mixing furfural with said products and then adding to said mixture an acidic sulphur removal agent selected from the group consisting of sulphuric acid and aluminum chloride, and in quantities sufiicient to remove or render inert the sulphur content of said products, while inhibiting the polymerization of unsaturated compcnents of said products.

6. The method of removing sulphur impurities from petroleum products'which comprises reacting upon said products at the same time with a mineral acid and furfural in amounts suflicient to remove or render inert a substantial proportion of the sulphur content of said products While inhibiting the polymerization of unsaturated components of said products.

WILLIAM ALVAH SMITH. 

